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Related Links:

Datasheets:
A3986: Dual Full-Bridge MOSFET Driver with Microstepping Translator (PDF)

Selection Guides:
Power Integrated Circuits,

Power Motor Drivers,

Power Motor Drivers - Full-Bridge

when this product is updated

A3986
Dual Full-Bridge MOSFET Driver with Microstepping Translator

Features

• 2-wire step and direction interface
• Dual full-bridge gate drive for N-channel MOSFETs
• Operation over 12 to 50 V supply voltage range
• Synchronous rectification
• Cross-conduction protection
• Adjustable mixed decay
• Integrated sinusoidal DAC current reference
• Fixed off-time PWM current control

Description

The A3986 is a dual full-bridge gate driver with integrated microstepping translator suitable for driving a wide range of higher power industrial bipolar 2-phase stepper motors (typically 30 to 500 W). Motor power is provided by external N-channel power MOSFETs at supply voltages from 12 to 50 V.

This device contains two sinusoidal DACs that generate the reference voltage for two separate fixed-off-time PWM current controllers. These provide current regulation for external power MOSFET full-bridges.

Motor stepping is controlled by the two-wire step and direction interface, providing complete microstepping control at full-, half-, quarter-, and sixteenth-step resolutions. The fixed-off time regulator has the ability to operate in slow-, mixed-, or fast-decay modes, which results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.

The translator is the key to the easy implementation of this IC. Simply inputting one pulse on the STEP input drives the motor one step (full, half, quarter, or sixteenth depending on the microstep select input). There are no phase-sequence tables, high frequency control lines, or complex interfaces to program. This reduces the need for a complex microcontroller.

The above-supply voltage required for the high-side N-channel MOSFETs is provided by a bootstrap capacitor. Efficiency is enhanced by using synchronous rectification and the power FETs are protected from shoot-through by integrated crossover control and programmable dead time.

In addition to crossover current control, internal circuit protection provides thermal shutdown with hysteresis and undervoltage lockout. Special power-up sequencing is not required.

This component is supplied in an 38-pin TSSOP (package LD). The package is lead (Pb) free, with 100% matte tin leadframe plating.

Functional Block Diagram

Complete Part Numbers

Part Number	Package Type	RoHS Compliant	Part Composition/ RoHS Data	Temperature	Comments	Samples	Distributor Stock
A3986SLD-T	38-lead TSSOP	Yes	view data	-20 °C to  85 °C	new
A3986SLDTR-T	38-lead TSSOP	Yes	view data	-20 °C to  85 °C	new	samples not available

Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system.